Some screening tests are able to see if your baby has a higher chance of chromosomal conditions. These conditions include Down's, Patau's and Edwards' syndromes. You do not have to these screening tests, but if you choose to, they happen at certain point in the baby’s development.
Your booking appointment is the first official antenatal appointment. It usually happens when you are between 8 and 12 weeks pregnant, and will ideally happen by the time you are 10 weeks. This means you can be offered the combined test. If you have your booking appointment later in your pregnancy, your midwife can offer you the quadruple test.
The combined screening test (10 to 14 weeks)
The combined test needs to happen between 10 to 14 weeks of pregnancy and consists of an ultrasound and a blood test. The results are used along with factors like your age, weight and smoking status to work out the chance of your baby having Down's, Patau's and Edwards' syndromes.
During the scan, the sonographer measures the fluid at the back of the baby’s neck. This is called a nuchal translucency measurement. This test needs to happen between 10 and 14 weeks because the nuchal translucency measurement will change after 14 weeks + 1 day. It is not always possible to get this measurement, depending on the baby’s position. If this is the case, you will be offered the quadruple test.
The quadruple test (14 to 20 weeks)
Unlike the combined yest, you can have the quadruple blood test after 14 weeks, but it can only screen for Down’s Syndrome. It is also not quite as accurate as the combined test. For Patau’s and Edwards’ syndromes, you will be offered a mid-pregnancy scan to check for physical abnormalities.
The non-invasive prenatal screening test (NIPT)
If you not been able to have the combined screening test or the quadruple test, some trusts offer a non-invasive prenatal screening test (NIPT). The NIPT works out the chance of your baby having Down’s syndrome and some other conditions. If you would like the NIPT and it is available to you then ask your maternity team for advice about whether it is suitable for your pregnancy. If your trust does not offer this test, you can have it through a private clinic. This usually costs between £350 to £550. If the cost is more, check what the test includes, most providers also include an ultrasound within the price.
You can have the test from 10 weeks until the end of pregnancy.
The NIPT includes:
• an ultrasound scan to confirm dating of your pregnancy
• a blood test to look at the small amount of your baby’s fetal cells in your blood.
If you want to go to a clinic for this test, check the clinic has a clear link with an NHS unit. This means that there will be a co-ordinated care pathway in place if your test result is positive.
What happens next?
No screening test is 100% accurate, these tests will tell you if you have a higher or lower chance of having a baby with one of these conditions. If you get a positive result and you may choose to get a diagnostic test to confirm the result or not. Your midwife will talk through your options with you, respect choices you make and offer you any support you need.